The present invention relates a power-saving method utilizing a function of a program such as a screen saver, a power-saving program and an information processor to which they can be applied.
Since power consumed by a graphics chip in a personal computer has been increasing recently, there have been introduced techniques for suppressing power consumed by a VRAM, a graphics memory, by reducing the frequency of clocks to be supplied or by stopping power supply as a part of power management (see patent document 1, for example). Such power-saving techniques for a VRAM is traditionally used for switching to a power-saving mode via suspend or hibernation.
In the case of switching to a power-saving mode via suspend or hibernation, the display condition of a monitor must be restored to the original condition before the switching to the power-saving mode when the mode is restored from the power-saving mode to a normal mode. Accordingly, the context of the VRAM is generally stored before switching, and after restoration to the normal mode, the context is recovered to the original condition before switching to the power-saving mode, based on the stored context. However, when the OS itself supports power management, the OS performs initialization of and image data re-creation on the VRAM when the VRAM is restored to the normal mode, and therefore storage of the context of the VRAM and restoration thereof based on the stored data are not required. In the case where an OS does not support power management as Windows®1 (registered trademark) NT 4.0, storage and recovery of the context of a VRAM are performed. The Windows mark is owned by the Microsoft Corporation.
On the contrary, in the case of an OS supporting power management such as Windows® (registered trademark) XP/2000/Me/98, there is provided a screen off timer function for powering off the monitor when a personal computer is left for a preset period of time. This function stops display of a LCD panel or an external CRT via an interface such as APM (Advanced Power Management), ACPI (Advanced Configuration and Power Interface) and DPMS (Display Power Management System) if there is no input from a keyboard or a mouse during a preset period of time, so that power consumption of the entire system can be saved.
(Patent Document 1)
Published Unexamined Patent Application No. 2000-298536
According to the prior-art techniques described above, however, when storing and recovering the context of a VRAM, area and time for storing the context is required. Especially when using a hibernation technique, it is necessary to store the context of a VRAM in a nonvolatile memory such as a hard disk. These days, the size of VRAM is increasing, and the data transfer rate for storage cannot be ignored. For example, in order to store the context of a VRAM with 64 MB in a hard disk, time of more than thirty seconds is required. Since the VRAM cannot be used during this time period, and the process progress condition cannot be displayed.
In a power-saving mode with a screen off timer, even when the monitor is powered off and display is unnecessary, supply of power or clocks to a VRAM is still continued.
A purpose of the present invention is to make a power-saving mode via suspend or hibernation available without necessity of storing contents of a VRAM and performing recovery based on the stored data even when an OS does not support power management, in consideration of the above problems of the prior-art technique. It is another purpose to enable supply of clocks or power to VRAM to be easily stopped without necessity of storing contents of a VRAM and performing recovery based on the stored data, when display on the monitor is unnecessary.